Below major mode is a dummy mode just derived from c-mode:
;; a simple major mode, mylang-mode
(define-derived-mode mylang-mode c-mode
"major mode for editing mylang language code."
(message "dummy"))
;; add the mode to the `features' list
(provide 'mylang-mode)
But when I switch on this mode by M-x mylang-mode, I always get below warning message:
Warning (irony): Major mode is unknown to Irony, see
`irony-supported-major-modes'.
I try to add below line to init.el but not helpful:
(add-hook 'irony-mode-hook 'irony-cdb-autosetup-compile-options)